Which of the following is diamagnetic?

Options

1. A\left[\mathrm{Cu}\left(\mathrm{NH}_3\right)_4\right]^{2+}
2. B$\left[\mathrm{NiCl}_4\right]^{2-}$
3. C$\left[\mathrm{PtCl}_4\right]^{2-}$
4. D\left[\mathrm{Cu}\left(\mathrm{H}_2 \mathrm{O}\right)_4\right]^{2+}